Lead zirconate titanate and barium titanate bi-layer ferroelectric films on Si

In this work, a novel method is proposed to integrate ferroelectric lead zirconate titanate (PZT) films on Si with highly tunable functionalities, through bi-layering with a barium titanate (BTO) film. First of all, the BTO film acts as a growth-promotion template layer which has successfully lowered the in situ deposition temperature of a ferroelectric PZT film. The PZT/BTO bilayer film deposited at 350 degrees C on LaNiO3-buffered Si substrate displayed a room temperature remnant polarization similar to 24 mu C/cm(2), and its quality can be further improved via a rapid thermal annealing (RTP) process. Furthermore, by changing their thickness ratio, various ferroelectric hysteresis loops (P-E loops) can be created in the PZT/BTO films, thereby enabling a broad range of applications for this simple bi-layer structure. Examples including high performance piezoelectric energy harvesters and high energy density dielectric capacitors are demonstrated for the PZT/BTO bi-layer films.